I can not touch the data stored in the production servers where the plugin API service is hosted for security reasons. So the best you can do is to generate a new API key, that is the fastest process. If you really need to recover that specific key because, for example, you want to keep the old security logs tied to your current website then I recommend you to contact me using this email address [1], refer this ticket in the message and one of my co-workers will forward the email to me.

For future references in case that someone else come across the same issue, it is possible to generate as many API keys as you want as long as the domain and email address are not used by other person. One of the things I do is to create a subdomain [2] on my website and use the same email address with a plus sign followed an unique identifier [3].